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Running engines at full throttle?

Discussion in 'Lawn Mowing' started by BAMARED, Feb 5, 2003.


    BAMARED LawnSite Member
    Posts: 206

    I talked to a close friend that I haven't seen in a while a few days ago. He's a mechanic by trade and has been doing this type of work for 40+ years and is highly regarded by many as one of the top and most respected mechanics in this area both for his skill level and his overall knowledge.

    We got on the subject of lawn mower engines. I told him that most mfg.'s of these lawnmower engines (Kawasaki, Kohler, etc.) recommend running their engines at full throttle when cutting grass. He told me that he didn't care what the mfg. of the engines say, that if you'll avoid full throttle operation as much as possible (but still get the job done) that it will extend your engine's life drastically. He went on to say that the reason that these mfg.s recommend full throttle operation is because they don't have to pay for a new engine and only benefit by telling the engines' owners this by increased sales of premature engine failure caused from excessive full throttle operation. Furthermore, he said that alot of equipment is designed to only produce the desired results under a full throttle load.

    I've got to respect what he told me about this, but was wondering what some of you guys think about this?


  2. walker-talker

    walker-talker LawnSite Platinum Member
    from Midwest
    Posts: 4,771

    If you don't run at full throttle, you are not going to get the maximum blade tip speed, which in turn will affect the quality of cut. I am not denying your friends opinion about making the life of the engine last longer, this might be true.

    When I price a lawn to be mowed, that price include running the throttle at full tilt.

  3. rodfather

    rodfather LawnSite Fanatic
    Posts: 9,501

    What your friend says makes sense. But what walker-talker brings up about blade tip speed and our ability to leave a lawn manicured is important as well.

    I've cited in the past that the mower manufacturers need to spend more of their R&D time and money not on building mowers with continually higher horsepower engines. But spending more effort on developing better air flow under the decks, greater blade tip speed, operator comfort, better controls, etc.

    Maybe with a more efficient and productive machine, we'll be able to turn down the rpm's some...dunno?
  4. 65hoss

    65hoss LawnSite Fanatic
    Posts: 6,360

    I've always done that. I run the mowers lower than full when conditions allowed it. When I needed the full amount it was there. For example I will run the lazer at 3400 if they situation will allow. But if need to I can spin it up to 3750.
  5. mklawnman

    mklawnman LawnSite Senior Member
    Posts: 634

    Was the dealer mechanic talking about at start up??? Cause I've been always taught that when opperating the mower to slowly increase the throttle to full when engaging the PTO. Even on our older JD's we do that, I've always thought that to make the machine run efficently and effectively that you need to run at full throttle when using the PTO, its constant for the engine to run at. True running at full throttle everytime is not good for the mower, but when using the PTO i would think you need to have the throttle full bore, use all the hp that you have to make the machine run smoothly.
  6. gorrell

    gorrell LawnSite Senior Member
    Posts: 536

    We always run all of our machines at full throttle. Air cooled engines are designed to be run that way to keep enough air circulating to facilitate the cooling process. Less than full throttle, less air circulating, more heat buildup. MHO............Lynn
  7. Doc Pete

    Doc Pete LawnSite Gold Member
    Posts: 3,469

    Your looking at this the wrong way. The motor is just another "consumable", like the mower itself, weed wacker or any other machine/item. The advantages and profit of running the motor at full throttle far out way the minimal amount of money saved by prolonging the life of the motor. FYI, treating the motor properly (oil changes, not lugging, clean air filter, etc.) are more important than running it a bit slower...... besides the fact that running it 10/15% slower will not make a noticable difference anyway..........FWIW, I have my original trim mower I had when I was 11, a 1961 hann eclipse pusher. Still has the orginal motor and doesn't blow smoke.........
  8. Randy Scott

    Randy Scott LawnSite Bronze Member
    Posts: 1,915

    It would last even longer sitting in my garage. Show me proven results and actual hours that would be extended by this low rpm practice, and it still wouldn't be worth the lower performance and results you would get. I think it might actually put MORE stress on the motor. There would be more resistance to the crank when hitting wet thick grass, poor fuel economy due to not fully burning cleanly or efficiently due to extra drag and stress on the motor.I think you may actually make things worse by this practice. Equipment is made to do a task. Like others have stated, this is figured into maintenance costs. I certainly don't recommend running wide open while it's sitting on the trailer warming up, or you stop to talk to an employee, but when using it for what it was designed for, cutting thick grass, you bet, WFO!
  9. Gravely_Man

    Gravely_Man LawnSite Silver Member
    Posts: 2,076

    I run everything wide open once the equipment has warmed up and I engage the blades at the lowest possible engine speed and then go to full throttle. I have always been told just as gorrell mentioned you need full throttle to keep the air flow up.

  10. lawnMaster5000

    lawnMaster5000 LawnSite Senior Member
    Posts: 589

    There is a reason these mowers have a governor.
    It prevents the engine from running at WOT even when the throttle control on the mower control panel is at "full throtle."

    When i run my mower i run it at "full throttle on the control panel - yet that is far below the engines WOT position.

    As others have stated its important to run your engines at recomended RPM for various reasons.

    An engine running WOT will be running above this recomended RPM, and yes will put excessive wear on an engine.

    Bomared - was your friend saying to run below recomended or just below the engines WOT - or max achievable RPM that an engine will be able to produce?

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